x/website: enable godoc analysis mode

[alml]

It would be useful to annotate interfaces in the godoc with list of known implementers.
Use case: I want to use text/scanner package and parse some data I receive from network. While reading its documentation I encounter a reference to io.Reader: https://golang.org/pkg/text/scanner/#Scanner.Init. I click on "io.Reader", and it would be nice to know that besides of net.TCPConn this interface is also implemented by bufio.NewReader, which can be used in my case.

Caveat: number of types implementing trivial interfaces can be huge.

[minux]

Have you tried 'godoc -http :6060 -analysis type'?

[bradfitz]

I think this bug is about having godoc's analysis mode enabled by default for golang.org

Related: #8968

/cc @alandonovan @adg

[alml]

Thanks! I missed "-analysis type" indeed. This does exactly what I asked for. And yes, it would be great to have it enabled on golang.org and godoc.org.

[minux]

Enabling it for golang.org is probably ok (it might also need an increase of the App Engine memory limit), but not for godoc.org (imagine how many outputs it will provide for commonly implemented interfaces like io.Reader or error; not to mention that the analysis must redo each time any package changes)

[alml]

Right, I mentioned this in the first post. It's a presentation issue, and I'm pretty sure it can be solved somehow. 1. Show "too many" if there are many implementers, possibly a href leading to a separate URL with full list. 2. Show some packages (most popular?) and ellipsis in the end. 3. Paginate the list. 4. Anything more smart.

[minux]

/cc @adg for enabling -type analysis on golang.org. For godoc.org, it might need some more work (I think we need to make the analysis incremental and not requiring loading all the packages into memory.)

[agnivade]

ping @adg

[bradfitz]

@andybons would be the owner of this now.

[bradfitz]

(It seems worth doing, unless we run into performance problems on start-up or ridiculous memory usage. If either of those occur, punt to a later release or Unreleased.)